Five children of asylum seekers detained at South Australia's Woomera Detentino Centre have attended their first day at St Barbara's Catholic Parish School at Roxby Downs in the state's north.

But principal Paul De La Hunty told the local ABC that it's unclear whether the two-day a week trial will be extended beyond this year.

"We haven't looked at the financial question of it yet," he said. "I've contacted the Catholic Education Office to get the ok, to let them know that it's happening, but to say that it is a trial and we're just going to look at it again at the end of this year and see what happens.

"It may continue and if it does continue there'll have to be resources put in place and a fee arrangement worked out," he said.